A. Technical Field
The present invention relates to energy efficient systems having linear regulators, and more particularly, to low power systems having integrated regulators.
B. Background of the Invention
A linear regulator is a system widely used to generate a steady voltage output. A typical regulating device is made to act like a variable resistor, continuously adjusting output impedance to maintain a constant output voltage.
Linear regulators are often inefficient in terms of power usage and waste a significant portion of the electrical energy by dissipating it as heat. FIG. 1 shows a conventional circuit 100 having a linear regulator 102. The rate at which electrical energy is dissipated by linear regulator 102 as heat is i1*(Vin−Vout), where Vin is the input voltage applied to linear regulator 102 and Vout is the output voltage of the linear regulator and is used to provide electrical power to circuit 104. The current i1 106 is the sum of current i2 107 and current i3 108.
The efficiency in power usage is an important factor considered in designing a circuit having a limited power supply, such as a battery. Even though linear regulators are inefficient compared to other types of regulators, such as switching regulator, linear regulators are still used in various circuits due to the low noise, short response time, low manufacturing cost, low area, and less strict requirements on input voltage. In such cases, circuit designers have to sacrifice the power efficiency in exchange for the advantages of linear regulators. As such, there is a need for a system that uses linear regulator without compromising efficiency in power usage.